The invention relates to a housing for an emergency call transmitter adapted to be mounted in a wristwatch.
Studies have shown that approximately 90 percent of injured persons of an aircraft crash survived the following six hours. Their chance of survival lies only at 10 percent after two days. Similar numbers apply also to travel by ship. Based on this fact, so-called ELT's (emergency locator transmitters) have been employed already for years for air travel that transmit signals for locating in the 121.5 MHZ or 243 MHZ band in case of emergency. These are relatively high-powered apparatuses mounted in the aircraft because of the large size related thereto.
In the year of 1979, the United States of America, the Soviet Union, Canada and France determined to develop and operate a satellite-aided locating system for emergency call transmitters the so-called COSPAS-SARSAT System (COSPAS is Russian for “Space System for the Search of Vessels in Distress”—SARSAT stands for “Search and Rescue Satellite-aided Tracking”).
COSPAS-SARSAT has since proven that worldwide, full-area monitoring for the location of emergency call transmitters causes considerable faster rescue. Low-flying satellites were employed thereby in a polar orbit at a height of approximately 800-1,000 kilometers—the so-called LEOSAR satellites (LEOSAR stands for “Low Earth Orbit Search and Rescue”).
COSPAS-SARSAT had six satellites in use in 1996. Overflight of each point on the earth surface was guaranteed thereby after approximately 45-50 minutes.
Detection of position was achieved by the use of the “Doppler effect”. However, inaccuracies are associated with this system.
Response to distress signals within a few minutes was not possible in most cases with the above-mentioned LOESAR satellite since approximately 45 minutes waiting time was necessary for an overflight of the satellite at the equator and approximately 25-30 minutes waiting time in the European latitudes.
The COSPAS-SARSAT System 1996. Overflight was expanded by the subsequently-described degree to eliminate both disadvantages:                1. An immediate response to distress signals is guaranteed now by three geo-stationary satellites—the so-called GEOSAR satellites (GEOSAR stands for “Geo-stationary Search and Rescue”), which are at a height of approximately 36,000 kilometers above the equator. They cover more than 80 percent of the earth surface—except for the polar caps.        2. Introduced were furthermore the transmission of exact position coordinates (e.g. by means of GPS, which stands for “Global Positioning System). Transmission is performed on the 406 MHZ band beside the individual emergency transmission code.        
The GEOSAR system showed in the test phase 1996/97 a response time to distress signals of only a few minutes in more than 95 percent of the cases.
Emergency call transmitters for the COSPAS-SARSAT system are commercially available, on one hand, as devices to be permanently mounted the respective aircraft or ships—or as portable hand-held devices. The disadvantage in such systems is the fact that the currently available devices are of relatively large size based on their stability and their battery life and that they are thereby only suitable for the above-mentioned employment purposes.
Swiss Patent (CH) 673 748 discloses a housing for a high-frequency transmitter that is inserted into a part of the back cover of a wristwatch housing. This part of the back cover is designed to be pivoted outwardly by means of hinges and it can be locked in place with the aid of a screw.
French Patent (FR) 2,692,708 describes a housing of a transmitter and/or receiver unit that has ended pieces which are formed to hold the wristband of a wristwatch so that said unit is held in place against the back of the wristwatch housing.
The object of the invention was therefore to provide an emergency call transmitter which can be employed universally and which can be carried along by anyone at all times without the need of an individually fitted holding device or the like.
This object is achieved according to the invention by an emergency call transmitter having the characteristics of the characterizing part of claim 1. An advantageous embodiment and development of the invention are shown in the minor claim 5.